The present invention relates to a method and equipment for implementing electronic cash through utilization of an electrical communication system, or a smart card or the like which records information.
Conventional electronic cash techniques or schemes are disclosed, for example, in Japanese Patent Publication 7-052460 entitled “Method and Apparatus for Implementing Electronic Cash,” Japanese Patent Application Laid-Open Nos. 4-367070 entitled “Electronic Cash Implementing Method,” 5-20344 entitled “Electronic Cash Implementing Method,” 7-302288 entitled “Electronic Cash System,” 8-87559 entitled “Electronic Cash Implementing Method and Electronic Cash System,” and 9-128465 entitled “Electronic Cash Implementing Method with A Trustee.”
In these electronic cash schemes proposed so far, electronic cash is attached with a signature of an electronic cash issuing institution (hereinafter referred to also as an issuer) for information which specifies the user of the electronic cash and the amount of money issued. The user stores the issued electronic cash in user equipment, and for each purchase, sends the electronic cash to a shop in a required amount. The shop makes a check to see if the electronic cash sent thereto is affixed with a valid signature, and if so, receives the electronic cash. The receiver, that is, the shop returns electronic cash information to the issuer for conversion. The issuer verifies the electronic cash information returned thereto to check for an improper use.
With the conventional electronic cash schemes mentioned above, the issuer manages information for each issuance of electronic cash, and the issued electronic cash returns via the user and the shop to the issuer, which checks the electronic cash for improper use. This method has such disadvantages as listed below.
The user is required to have a storage device for holding electronic cash issued to him.
The receiver, a bank and the electronic cash issuer are each required to have a device and time for verifying electronic cash.
The issuer is required to have a particularly large-capacity storage for storing information corresponding to electronic cash issued.
Since the user specifying information (pseudonym) is determined at the time of issuance of electronic cash, it cannot be changed to a different pseudonym when the user makes a payment by electronic cash.